1-aziridinyl alkyl phosphoramides



United States Patent Office 3,538,080 Patented Nov. 3, 1970 ABSTRACT OFTHE DISCLOSURE FIELD OF THE INVENTION This invention relates to a novelprocess for preparing compounds containing from one to threel-aziridinyl alkyl groups and to novel compounds containing two or threel-aziridinyl alkyl groups so produced. More particularly, this inventionrelates to novel his and tris(1- aziridinyl alkyl) phosphoramides and toa process for preparing l-aziridinyl alkyl phosphoramides froml-aziridinyl phosphoramides and aziridines.

DESCRIPTION OF THE PRIOR ART Aziridinyl phosphoramides, such astris(1-aziridinyl) phosphine oxide, are known in the art. They aretypically prepared, for example, from an aziridine and phosphorusoxychloride. Such aziridinyl phosphoramides have found only limited useas curing agents for acid terminated polymers (e.g., carboxy terminatedpolybutadiene) because they are isomerized during curing, resulting inunpredictable and often unsatisfactory cure properties and because theytend to degrade on aging, causing cure reversion.

SUMMARY OF THE INVENTION According to the present invention, novel bisand tris(1-aziridiny1 alkyl)phosphoramides, which are substantially freeof the above undesirable characteristics when used as curing agents foracid terminated polymers, are provided by modifying l-aziridinylphosphoramides with an aziridine. The novel compounds of this inventionhave the general formula:

(1) R is, independently in each case, hydrogen or an alkyl group havingfrom 1 to 4 carbon atoms,

(2) A is (R N- or R (3) R is an alkyl group having from 1 to 4 carbonatoms, and

(4) n is 0 or 1.

wherein:

The compounds having the above general formula, as Well as l-aziridinylalkyl phosphoramides wherein n in the above general formula is 2, may beprepared by contacting at least an equimolar quantity of an aziridinehaving the formula:

with an aziridinyl phosphoramide having the formula:

wherein A and R are as defined previously, and n is 1, 2, or 3, at atemperature between 50 and 250 C. under at least autogenous pressure fora time suificient to allow the resulting reaction to go to completion.

DETAILED DESCRIPTION OF THE INVENTION Operable aziridines for use inthis invention include ethylenimine and such alkyl substitutedaziridines as 1,2- propylenimine, 1,2-butylenimine, 2,2-butylenimine,and the like. Preferred aziridines for practice of this invention areethylenimine and 1,2-propylenimine.

Suitable specific examples of aziridinyl phosphoramides for the presentinvention include tris(1-aziridinyl) phosphoramides, such astris(l-aziridinyl) phosphine oxide, tris(2 methyl 1 aziridinyl)phosphine oxide, tris- (2,2-dimethyl-l-aziridinyl) phosphine oxide,tris(2-isopropyl-1-aziridinyl)phosphine oxide, tris(2-n-butyl-1-aziridinyl)phosphine oxide, and the like; bis(l-aziridinyl) phosphoramides,such as bis(l-aziridinyl) (diamino) phosphine oxides, e.g.,bis(l-aziridinyl) (dimethylamino) phosphine oxide, bis(l-aziridinyl)(diethylamino) phosphine oxide, bis(l aziridinyl)(diisopropylamino)phosphine oxide, and the like; bis(l-aziridinyl)(alkoxy)phosphine oxides, e.g., bis(l-aziridinyl) (methoxy)phosphineoxide, bis(l-aziridinyl) (ethoxy)phosphine oxide, and the like;l-aziridinyl bis(diamino, or alkoxy) phosphoramides, e.g., l-aziridinylbis(dimethylamino) phosphine oxide, 1-aziridinyl bis(diisopropylamino)phosphine oxide, 1- aziridinyl bis(methoxy) phosphine oxide,l-aziridinyl bis(ethoxy)phosphine oxide, and the like.

In practice, the compounds of this invention are prepared by contactingan aziridine and a l-aziridinyl phosphoramide in a mole ratio of atleast 1:1 in the case of mono(1-aziridinyl alkyl)phosphoramide, at least2:1 in the case of bis(l-aziridinyl alkyl) phosphoramides, and at least3:1 in the case of tris(1-aziridinyl alkyl) phosphoramide. The reactantsare desirably introduced to a presure vessel, such as a stainless steelbomb, and heated at a tempearture between 50 C. and 250 C., preferablyto C., under autogenous pressure for a time suflicient to allow theresulting reaction to go to completion, usually from about 10 minutes to5 days, depending on the aziridine, the l-aziridinyl phosphoramide, andthe temperature conditions employed.

Pressure additional to that generated autogenically may be employed ifdesired, but no apparent advantage is obtained thereby.

At least a mole ratio of the aziridine to l-aziridinyl phosphoramidecorresponding to the number of aziridine rings on the l-aziridinylphosphoramides should be used in the reaction. Mole ratios from thisminimum up to about 50:1 have been found advantageous, with mole ratiosof aziridine to l-aziridinyl phosphoramide of about 10:1 to about 30:1being preferred.

The reaction may be carried out either in the presence or absence of aninert reaction solvent. As used herein, the term inert means that thesolvent is non-reactive with the aziridine, the l-aziridinylphosphoramide, and the resulting l-aziridinyl alkyl phosphoramidereaction product under the reaction conditions employed. Suitablespecific examples of such inert solvents, which may be used singly or asmixtures, include the lower alcohols, such as methyl alcohol, ethylalcohol, i-propyl alcohol, n-butyl alcohol and the like; aromatichydrocarbon solvents, such as benzene, toluene, and the like; aliphaticketones, such as acetone, methyl ethyl ketone, and the like, dialkylethers, such as diethyl ether, and the like. The preferred inertreaction solvent is ethyl alcohol.

The reaction between the aziridine and the l-aziridinyl phosphoramideshould be carried to completion. If the reaction is incomplete, theresulting product tends to be unstable with respect to polymerization.

The l-aziridinyl alkyl phosphoramides of this invention are useful ascuring agents for a wide variety of polymers, for example,styrene-maleic anhydride copolymers, acid terminated polymers (e.g.carboxy-terminated polybutadiene), and the like. The novel his and tris(laziridinyl alkyl) phosphoramides are particularly useful for curingcarboxy terminated polymers because they do not isomerize during curing,nor do they undergo cure reversion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following non-limitingexamples describe preferred embodiments and illustrate the inventionfurther.

EXAMPLE 1 A stainless steel bomb was charged with 25.4 grams of an 80percent by Weight solution in ethyl. alcohol of tris(1-aziridinyl)phosphine oxide (0.117 mole) and 300 ml. of ethylenimine (5.80 moles).The bomb was closed, heated at 120 C. for /2 hours and allowed to cool.Removal of the excess ethylenimine under vacuum left 38.8 g. (100percent yield) of a clear, viscous liquid which was analyzed by infraredspectroscopy and found to have a spectrum consistent with the followingstructure:

The compound of Example 1 was found to be useful as a curing agent forpreparing coating compositions as follows:

A 1 g. sample of a copolymer of styrene-maleic anhydride (50 percent byweight of maleic anhydride, approximately a 1:1 mole ratio) wasdissolved in 5 ml. of methyl ethyl ketone. A second solution, consistingof 0.50 g. of the compound of Example 1 dissolved in 5 ml. of methylethyl ketone, was mixed with the first solution. The resulting mixturewas poured onto a bonderized steel 4 panel (4 x 12 x inches). Thesolvent was evaporated and a film of 0.5 mil (0.0005 inch) thicknessresulted. This film was cured at C. for 30 minutes. The cured coatinghad excellent adhesion properties, was not affected by water and hadgood impact strength on the surface of the film.

EXAMPLE 2 A product similar to that of Example 1 is obtained whenethylenimine and bis(1-aziridinyl) (dimethylamin0)- phosphine oxide in amole ratio of 10:1 are allowed to react under the same conditions as inExample 1.

EXAMPLE 3 A product similar to that of Examples 1 and 2 is obtained when1,2-propylenimine and tris(l-aziridinyl) phosphine oxide in a mole ratioof 1521 are allowed to react under the same conditions as in Example 1.

What is claimed is:

1. A compound of the formula:

wherein: (1) R is, independently in each case, hydrogen or an alkylgroup having from 1 to 4 carbon atoms, A is 1)2 (3) R is an alkyl grouphaving from 1 to 4 carbon atoms,

and (4) n is 0 or 1.

2. A compound as in claim 1 wherein n is 0 and R is hydrogen.

3. A compound as in claim 1 wherein n is 0 and R is hydrogen or methyl.

4. A compound as in claim 1 wherein R is methyl, ethyl or isopropyl.

References Cited UNITED STATES PATENTS 2,889,289 6/1959 Reeves et a1.260239 3,359,259 12/1967 Ham 260-239 FOREIGN PATENTS 63,864 8/ 1949Netherlands.

ALTON D. ROLLINS, Primary Examiner U.S. Cl. X.R.

